This is the story of Billy the mayfly. Entomologists call him by his Latin name - Ephemerella excrucians. Fly fishers call him a Pale Morning Dun. Billy doesn't know his name, but he does know what it is like to live as a tiny mayfly on the bottom of a large river. His life is full of danger, but also full of amazing changes. Read on to see what these changes are and if Billy lives to fulfill his final quest.